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Load for LM7321

Mass Garp
Prodigy 210 points

Other Parts Discussed in Thread: LM7321, LMH6629

Hi,

I use  opamp LM7321 in a buffer configuration. It should drive 100pF capacitive load. Should I provide to connect also a resistive load in parallel with CL?

From simulation on TINA software I see that results are good with only load capacitor.

Thanks

  • 0
    TI__Guru 69066 points

    Hello Mass,

    The LM7321 is designed to directly drive capacitive loads without series resistance, so 100pF should not be a problem.

    It does not need any parallel resistive loads or snubbers for stability.

    Regards,

  • 0 in reply to Paul Grohe
    Prodigy 210 points

    Than you so much, Mr Grohe.

    Now I have another little doubt. I have an application that uses LMH6629 as active filter. It should drive a capacitive load, about 100pF. As far as I see on the datasheet there aren't recomendations about driving capacitive load, except a picture in which a parallel resistor RL is introduced. How must I behave in this case? I should put this parallel resistor or a series resistor?

    Thanks.

  • 0 in reply to Mass Garp
    TI__Mastermind 22825 points

    Hello,

    For the LMH6629 stability vs. 100pF load:

    It is probably best to do your own evaluation on your PC board which includes all parasitic elements, etc. You could do so with a step response and look for under-damped ringing and overshoot or, instead look for sharp frequency response peaking as indication of need for output resistor to isolate the capacitive load.

    The LMH6629 datasheet does show the frequency response for several capacitive loads under very specific conditions and it includes "Riso" (isolation resistor to reduce peaking), shown below for your reference:

    Regards,

    Hooman